object-auditor process consume disk I/O

on my storage node, the disk IO speed I got with the help of "time dd if=/dev/zero of=/srv/node/sda3/test bs=1M count=2000" is about 120MB/s;
But, once the object-auditor process of storage nodes is on, the IO speed will decrease violently, because the object-auditor has been always reading disk and generating read IO speed about 10MB/s. This case makes the whole speed of swift very slow.
Once I stop the object-auditor process, the speed of swift becomes very quick.

I knew that object-auditor process's function is to ensure the integrity of objects/container/account, but is it neccessary to keep it always on? Perhaps there is something wrong of my configure. So I need some advice and help, Thanks!

The zero byte check can be run at a much faster speed and causes less load because it only looks at zero byte files and doesn't read through the entire files for an md5 for verification of the file's etag. The zero byte file is much more common problem. We run it after we have system failures on a object-server.